Method and apparatus for conditioning air



' Dec. 12,1939;

C. R. DOWNS METHOD AND APPARATUS FOR CONDITIONIMI' AIR Filed June 25, 1937 4 Shets-Sheet 1 I INVENTOR CHARLES Dec, 12, 1939. v

c. R. DOWNS 2,183,136

METHOD AND APPARATUS FOR CONDITIONING AIR Filed June 25, 1937 4 Sheets-Sheet 2 F0 a l 125. 3.

INVENTOR Dec. 12,1939. c. R. DOWNS 2,183,136

METHOD AND APPARATUS FOR CONDITIONING AIR Filed June 25,1937 4 SheetsSheet 3 'ZO 14 I 44 INVENTOR CHARLES R.

Dec. 12, 1939. DOWNS 2,183,136

METHOD AND APPARATUS FOR CONDITIONING AIR Filed June 25, 19:57 4 Sheets-Sheet 4 Patented Dec. 12, 1939- UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR CONDITIONING Am Charles R. Downs; Old Greenwich, Conn, as-

signor, by mesne assignments, to The Calorider Corporation, Greenwich, Conn, a corporation or Connecticut Application June 25, 1937, Serial No. 150,230

re Claims. (Cl. Isa-12c) lid This invention relates particularly to the conditioning of air or other gases by means of dehumidiflcation by processes in which it is necessary to remove heat from and cool the air which the water discharged by the apparatus is conducted and passed in contact with atmospheric air and the water so cooled is returned to the apparatus and then used to extract heat or gases and dehumidifying agents during the from a moisture absorbent material after which 5 operation oi the air or gas conditioning unit, the water is recycled through the cooling tower but it may also be used for the removal of other for recooling by evaporation. For the purpose vaporous constituents from air or other gases of obtaining cooler water than can be produced by suitable absorbents. The invention relates by its evaporation in contact with atmospheric iii both to the method and to the apparatus in air, the use of predried air has been proposed. lb which the method may be practiced. Heretofore known methods of using cooling In methods of conditioning gaseous fluids by towers. for this purpose are objectionable for the means of dehumidiiication using moisture abreason that the cost of installation is high hesorbing materials in either liquid or solidform, cause the point of location of the cooling tower heat is liberated and unless removed, the moisis separated from the air conditioning apparatus lb ture absorbing materials rise in temperature. requiring extensive piping and pumping equip- If this rise is not restrained further moisture ment for taking the water which has absorbed I removal from the gaseous fluid ultimately stops. heat to the tower and returning the cooled When solid absorbing materials are used this water to the air conditioner for further heat at cooling is generally primarily effected by trarisabsorption. The cost is further increased by ter of heat to the gaseous fluid being dehumidithe necessity for lagging the cooling water refied. When liquid moisture absorbing materials circulating equipment from the cooling tower to are used they are generally removed from the the air-conditioning apparatus and return, the conditioning zone, heat previously absorbed by cooled water from the cooling tower is heated to them is extracted therefrom and the cooled liqsome extent by conduction through the equip- 25 uid returned to the conditioning zone to absorb ment walls and also somewhat by the mechanical further moisture and heat.- Similar methods energy required to force the water through the have also been employed for removing other resistance of the piping circuit. When the atvaporous constituents from air or other gases. mospheric dew .point is high the cooling. water tit 111 e p ding applications'ser. Nos. 57,148 additionally gains some heat due to condensaand 98,646 of Charles R. Downs and Joseph W. tion of moisture externally on the pipe walls or Spiselman methods and apparatus are shown other parts unless this is prevented by the use and described in which latent heat of condenof special and expensive moistureproof insulasation of moisture is converted to sensible heat tion. Heat is also introduced from similar ex- Ed and together with sensible heat in the air or ternal sources through the walls and supports gaseous fluid entering the apparatus is absorbed of the cooling tower and the air conditioning by a liquid moisture absorbing material and exapparatus. When the cooling liquid is cooled tracted at the moment of absorption by a coolby any other outside cooling means the same ing fluid such as water which is in indirect heat type of disadvantages are met.

40 transferring relationship with the liquid mois- It is an object of my invention to reduce ex 40 ture absorbing material. The cooling water carternal heat gains into a gas conditioning system lies the heat away from the process or apparatus. to a minimum by providing an apparatus and v Where city or well water has been usedras the method in which the gas is purified of vapors .-cooling fluid, the cost of the water required to or other gases to an unsaturated condition and carry away the heat has been an important faccooled in a gas conditioning chamber combined 45 tor in the cost of carrying out the process and with an evaporative water cooling chamber where there are many instances where the water obcool'wateris produced for cooling the former tained from natural sources is at too high a temin such manner that the apparatus may be inperature' to eflect adequate cooling especially stalled or used as a single unitary structure.

where the air must be cooled to temperatures The evaporative water cooling chamber may be 50 considerably below that of the space to which one in which water is cooled by vaporization into it is to be transferred. a stream of either ordinary atmospheric air To reduce this cost and to conserve water or air which has been predried or in which supplies proposals and attempts have been made water is evaporated under the application of a to use an evaporative water cooling tower to partial vacuum. The vapors or other gases re- Another object of my invention is to provide.

a water evaporative cooling chamber and an absorption air dehumidifying chamber in a unitary structure which can be installed in a restricted space without the necessity of extensive alterations to the building or of extended lines of piping and ducts for connecting a separated cooling tower to a dehumidifying unit since all the heat resulting from the production or dried and cooled air is removed directly from the structure itself in the form of water vapor.

Another object of my invention is to provide an air conditioning apparatus in which air is dehumidified to a moisture unsaturated state by a 'hygroscopic liquid flowing concurrently therewith through a dehumidifying chamber combined with an evaporative cooling jacket for the dehumidifying chamber to form a unitary structure of high efficiency and in which surfaces common to both eilect desirable heat transfer in such a manner that the cooling effect of the evaporative cooling jacket is concurrent to the fiow of air and hygroscopic liquid.

A further object of my invention is to provide an evaporative cooling chamber and an air delmrnidifying chamber as one structural unit in such manner that two or more of these units may be conveniently connected together so that the moisture unsaturated air from the first unit may be conveyed to the evaporative cooling chamber of the second unit to remove heat from the second unit to thereby produce a lower temperature in the dehumidifying chamber of the second unit and thereby permit conditioned air of lower moisture content and lower temperature to be delivered from the second or any later unit in the series than would be possible by the use of only a single unit. 7

A further object of the invention is to produce moisture unsaturated air by contact with a cooled hygroscopic liquid in an air conditioning chamber, divide the air so produced into two streams one of which is passed through an evaporative water cooling chamber in which the cooling efiect so produced is concurrent to the flow of hygroscopic liquid in a dehumidifyihg chamber used to further dry and cool the second stream of air.

A still further object of the invention is to provide a system whereby air may be cooled during absorptive dehumidification solely by evaporative cooling within a unitary structure in such a way that air so conditioned may be discharged therefrom at a temperature or moisture content each suitable for comfort conditioning even under extreme atmospheric conditions and at the same time to obtain these results with a minimum of equipment, occupying a minimum of space at a low operating cost.

Various other objects and advantages of my invention will appear as this description proceeds.

In one form of dehumidifier-cooler according to the present invention the cooling water passing through the dehumidifier portion is discharged directly to its evaporative cooling jacket where it is sprayed down countercurrent to a stream of air.rising through this jacket. As the water cools as it proceeds downward, its cooling effect transmitted through the common wall of the dehumidifier and jacket is concurrent to the flow of dehumidifying solution inside. Just as with the internal cooling water'in the heat exchange unit of the concurrent flow dehumidifier, the temperature decreases from top to bottom despite the fact that it is flowing in the opposite direction.

The use of the annular space around the dehumidifier to form the evaporative cooling jacket allows a large available cross section which enables the height of the apparatus to be kept down and at the same time the outside dimensions of the entire equipment are at a minimum.

This new form of apparatus has made it possible to carry out very efficient air conditioning operations, including both dehumidification and cooling of the air and by including certain additional provisions both functions can be maintained regardless of outside atmospheric conditions. Independence of outside atmospheric conditions may be accomplished by supplying the evaporative cooling jacket with air, the wet bulb temperature of which is satisfactory or has been adjusted to a desired point, thereby enabling the jacket to remove heat from the unit in the form of moisture vapor and at a lower temperature than could be accomplished with outside air under adverse weather conditions. For such purposes, forexample, two dehumidifier-cooler units each comprising an extended surface heat exchange dehumidifier and its evaporative cooling jacket may be employed. In one of these units atmospheric air is dehumidified and cooled to the extent possible by using a circuit of cooling water whose temperature is continuously adjusted by contacting with atmospheric air in the evaporative-cooling jacket of the first dehumidifier-cooler. This dehumidified and cooled air is then used in the evaporative cooling jacket of the second dehumidifier-cooler, which cools and dehumidifies the air designed to be used in the conditioned space.

By this system the hygroscopic solutions or other hygroscopic material convert the latent heat load of the air to be treated into sensible heat and this plus the sensible heat of the entering air is removed in the form of water vapor. The heat in the first dehumidifier-cooler may be removed at a relatively high temperature level where evaporative cooling with atmospheric air in the evaporative jacket portion will sufilce and the so treated air will develop a materially lower temperature level in the evaporative cooling jacket of the second dehumidifier-cooler so that the air treated therein can be completely adjusted to thebonditioning requirements. When a second dehumidifier-cooler is used in series, the humidity and the temperature of the air delivered to the conditioned space can be independently controlled, the former by the conditions of the dehumidification operation and the latter by the character of the air supplied to the evaporative cooling jacket. Under some conditions atmospheric air or air taken from the conditioned space or a mixture of outside and inside air may a be used in the evaporative cooling jackets of either one or more of the conditioned units.

When the air to an evaporative cooling Jacket of a dehumidifier-cooler is first. treated by a dehumidifier, the heat may be removed from this dehumidifier by any suitable means, such as city water, well'water or recycled water from an ordinary atmospheric cooling tower or by water evapcrating under a vacuum in an evaporative cooling jacket surrounding the dehumidifier.

In the system of air conditioning herein provided only a relatively small portion of the energy input into the'system is in the form oi electric energy to transport air and liquids. The bulk-oi the energy input, that is the requirements to remove the latent and sensible heats of the air conditioned, is supplied to the system in the form of heat to the concentrator and this heat may be applied in any form so that the cheapest av'ailable fuel source will be adequate. Moreover the system conserves and utilizes this energy in a highly efiicient manner so that operating costs.

are below those of heretofore known systems. Moreover advantage is taken of any moisture unsaturation of atmospheric air or other air which is available and this potential energy is substantially completely utilized in the system.

The foregoing discussion has considered only two units in series, but the scope of the invention includes a series of any desired number of units in which the air produced in one unit is used in the evaporative cooling jacket of the unit next in the series thereby producing colder and colder water through the series and consequently colder and colder air which at the same time is lower and lower in absolute humidity from one to the other of the units in the series to a practical limit.

While the dehumidifying-cooler unit described and illustrated herein is of the concurrent flow solution type as described in copending applications Ser. Nos. 57,148 and 98,646, it will be understood that other types of dehumidification units may be incorporated into a unitary structure with an evaporative cooling jacket as described herein to form a dehumidifier-cooler.

In the form of embodiment of the invention illustrated in the accompanying drawings:

Fig. 1 is a sectional view of a preferred form of embodiment in which theevaporative cooling jacket surrounds a dehumidifying unit of the type described in copending application Ser. No. 98,646.

Fig. 2 is a sectional plan view on the line 2-2 of Fig. i;

Fig. 3 is a sectional view on the line 3-3 of Fig. 1;

Fig. 4 is a diagrammatic view illustrating the use of two or more units in series with a single .reconcentrator for the hygroscopic solution;

Fig. 5 is a sectional view substantially on the line oi Fig. 3; g v

Fig. 6 is a sectional view 0! a modified form of apparatus in which a soft water or other cooling liquid circuit is used for the heat exchange unit of the dehumidifier;

Fig. 7 is a sectional view showing a dehumidi her-cooler portion comprising an evaporative cooling jacket and a liquid phase dehumidifier which also supplies cooled water to the solid drying zone of the type shown and described in co pending application Ser. No. 57,148; and

Fig. 8 is a schematic view showing the air from one dehumidifier-cooler unit divided and part used for cooling the water of a second unit while the remainder is passed through the dehumidification portion of the second unit to be further cooled and dehumidifled.

In Flgures 1, 2 and 3 the numeral i represents a dehumidifier-cooler which comprises a concurrent flow extended surface heat exchange dehumidifier 2, and an evaporative cooling jacket 3. The dehumidifier portion 2 contains an air inlet duct 4, a. series of pipes 5 and hygroscopic liquid spray nozzles 6, an extended surface heat exchange unit 1 containing conduits 8 and fins 9, as described in said copending application Ser. No. 98,646, a chamber l0 containing an air deflecting bafiie II which may be perforated for drainage of liquid as shown by the arrows in Fig. 1 and a sump M, an outlet section it containing spray eliminators i l and 25 from which curtains Ma and a hang downwardly and whose bottom edges are sealed by the liquid in sump 62 to prevent air from bypassing the spray eliminators it and It and an outlet opening it through which the air which has been conditioned is discharged for use. The evaporative cooling jacket 3 surrounds all four sides of the dehumidifier portion 2 and is separated therefrom by a heat conducting wall 27!. Figure 1 shows a plate i tb which is provided with small liquid drainage holes to permit the small amount of liquid separated from the air by the eliminator l5 to drain into sump F2.

Jacket 3 constitutes an annular space whose outside walls are shown as 88, which are preferably lagged, its ceiling as 59 and its floor as 28.

Within the jacket 3 a pipe 2! encircles the portion 2 and is provided with nozzles 23 for creating sprays of water. Below spray nozzles 23 the jack t 3 may be provided with a filling material 26, which may he composed of slats, hurdles, Raschig rings, Berl saddles or other bafiing means for spreading out thin layers of water over very extended surfaces. When this filler 2% is of a loose type it may be supported upon screens 25. Below the filling material 2% and above the floor 25, I prefer to provide an open annular space '26 surrounding portion 2 inorder to distribute air to all parts of the evaporative jacket 3 from air inlet 2?. Air is discharged to waste through outthe openings l5b and 29:: after whichthey may water pump 32 has a short inlet pipe 33 leading from the space above the floor 26 and it discharges through a short pipe 34 to the inlet or header 35 for the tubes 8 of an extended surface heat exchange unit .I in the dehumidifying zone or chamber 2. Wherever pipes 33 and 34 extend beyond the walls of the unit, I prefer to thoroughly insulate them. The outlet header 36 of the heat exchange unit I is connected by pipe 31 to pipe 2| which is provided with spray nozzles 23, said pipe encircling the upper part of the "evaporative cooling jacket zone 3. As water is evaporated in jacket 3 and is carried ofi with the discharged air through 28, make-up water is led through pipe 40 and valve 4| which is under the control of float 42 to maintain a layer of water upon the fioor 20.

The pump 3.I has its suction connected to sump I2 for the hygroscopic liquid by means of pipe 43 and its discharge ,connected to pipe 44 which is branched to connect to pipes 45 and 46. These pipes are valved at 45a and 46a respectively to proportion the quantity of hygroscopic liquid discharged through each and are preferably short and insulated. Branch 45 leads to header 4! and pipes 55 provided with nozzles 6. As the hygroscopic liquid removes water from the air passing through the dehumidifier 2, it becomes more dilute and this water must be removed, hence a portion of the hygroscopic liquid is continuously discharged through branch 46 to a reconcentrator as shown for example in copending applications Ser. No. 98,646 and Ser. No. 144,630 wherein its construction and operation are described in detail or to any other suitable type of concentrator. Concentrated hygroscopic liquid is returned from the reconcentrator to sump L? by pipe 56.

The operation of the dehumidifier-cooler unit is as follows. Air enters the dehumidifier zone 2 of the unit I through the air inlet 4 and contacts with the sprays 6 of hygroscopic liquid such as water solutions of calcium chloride, lithium chloride or the like. The air in a plurality of thin streams passes through narrow channels formed by arranging the fins 9 in closely spaced substantially parallel order and the hygroscopic liquid spread in thin films upon the heat conducting surfaces or fins 3 fiows concurrently with the air through the extended surface heat exchange unit I. The hygroscopic liquid while absorbing moisture from the air absorbs the latent heat of condensation of the condensed moisture and sensible heat from the air and this heat is transferred at the instant and position of formation or absorption to the water flowing inside the tubes 8 of the heat exchange unit I. The air and hygroscopic liquid leave the heat exchange unit 1 in substantial equilibrium with each other and at the lowest temperature reached in the dehumidifying zone and separate from each other in chamber ID, the hygroscopic liquid flowing down the Perforated bafiie II to the sump I 2 for recirculation through the unit and the air passing through the eliminators I4 and I5 to the outlet l6 from which it is discharged to the space to be conditioned or to another conditioning unit in the series, as described later.

In the application Ser. No. 98,646, the cooling fluid used for removing the heat from the extended surface heat exchange unit I was obtained from any suitable source. construction, the cooling fluid is water and its temperature is continuously adjusted by evaporating water within the apparatus itself.

Air from any suitable source is caused to enter the inlet 21 by means of a blower 28a and pass through the space 26 surrounding the wall I! under the screen 25. It then passes upwardly through the evaporative cooling jacket 3 which may be an unfilled space but is preferably filled with suitable bafiles which are wetted by a downward flow of water originating from the spray nozzles, 23. The counterfiowing air evaporates a portion of the downfiowing water and air of high relative humidity carrying away the heat discharges to waste through 28 for example to the outdoor atmosphere. Care should be taken to prevent the discharge of this air closely adjacent to the air inlet 4 for the dehumidification unit 2,

should this draw air from outdoors, so that the In the present heavily moisture-laden air from 28 will not short circuit into air inlet 4 or into air inlet 21, should this be designed to receive its air from outdoors. This requirement can be satisfied by the use of properly placed ducts. I prefer to use a blower to draw air from the evaporative jacket rather than force it into the same as by this means the air entering the jacket is not heated by compression.

The water, in excess of that evaporated, having been cooled by the evaporating water drains on to the fioor 20 and is forced by pump 32 directly through the heat exchange unit I of the dehumidifier 2 back to the nozzles 23. Entrained water is separated from the air before it discharges through outlet 28 by the spray eliminator 29. Any unavoidable loss of water due for example to poor elimination plus that loss by evaporation is made up by means of the float valve 42 and the water inlet valve 4!. The water resting upon the floor 20 is the coldest portion of the water in the circuit while that discharged from the nozzles 23 after having passed through the heat exchanger I is the warmest portion at any moment. As the water flows down through the evaporative cooling jacket 3 its temperature is decreased and the wall i7 is progressively cooled toward the bottom of the heat exchange section 1. The temperature differentials of the water in the various parts of the circuit may not be great if the rate of circulation is rapid. I thus provide progressive cooling of the descending hygroscopic liquid and air in the chamber 2 both internally and externally. In additionto this I provide by means of jacket 3, a method of insulating the dehumidifier section I from outside heat.

To prevent heat from being transferred from the surrounding atmosphere into the evaporative cooler jacket 3, I prefer to cover its exterior with suitable heat and moisture insulation and a considerable saving in cost of installation is permitted in that the lagging of the wall I! is rendered unnecessary. The compact nature of my dehumidifier-cooler permits the shortest possible pumping lines, thereby reducing resistance to liquid flow, reducing cost of piping and of pipe lagging to prevent heat absorption by the flowing liquids. Opcrating costs are reduced and heat losses are at a minimum and the compactness of the unit requires a minimum of floor space.

Ample evaporative cooling surfaces may be provided with the screens 25 located as illustrated without increasing the height of the jacket 3 or increasing its horizontal dimensions beyond the proportions shown. For example the horizontal dimensions of the dehumidification chamber 2 may be three feet square giving a face area of -nine square feet for the extended surface heat exwater passed through tubes 8 of heat exchange unit 1, is also of advantage when for example the evaporative jacket 3 is to be operated under vacuum. In such a case, the inlet 21 is sealed or not provided, and a means of evacuating the jacket 3 is connected to outlet 28.. As shown in Fig. 4. the inlet 21 may be closed by a damper or valve 21a to prevent intake of air to the jacket. The blower 28a will thus suck air from the jacket and create a partial vacuum, facilitating the evaporation of water in the jacket. Any other suitable means for closing the inlet and for creating a partial vacuum in the jacket may be employed.

Independent control of the temperature and humidity within a space conditioned for comfort can be provided by the dehumidifier-cooler as described herein. To attain this objective, a thermostat in the conditioned space C may be used to control the temperature thereof by varying the temperature of the produced conditioned air by varying the degree of vacuum in the evaporative cooling chamber or by varying the quantity of moisture evaporated to the air passed therethrough to be humidified and a humidostat similarly placed may be used to control the moisture content of the space by varying the moisture absorbing character of the hygroscopic liquid by varying its concentration. One method of doing this is illustrated diagrammatically in Fig. 4. The thermostat D in the conditioned space C controls the speed of the motor of the blower 28b to vary the extent of partial vacuum in the jacket,

and a humidostat E in the conditioned space controls the regulating valve 46a so as to control the how of hygroscopic liquid to the concentrator 55. Spaces containing other gases may be controlled similarly.

The air passed into inlet} of the dehumidifica tion unit 2 may be all outdoor air or air recirculated from the conditioned space or a mixture of the two depending upon the amount of ventilation required in the conditioned space or it may be air which has been reduced in another suitable apparatus below the temperature and/or moisture content of outdoor air. The air discharged from outlet l3'may all be sent to the conditioned space or it may all be discharged to the evaporative cooling jacket of a second air conditioning unit for the purpose of producing a lower temperature therein than can be attained when using untreated air or it may be passed through an evaporative cooling tower of any suitable type for producing cold water for various uses, or it may be divided and part used for evaporative water cooling and part further dehumidifled as described in connection with Fig. 8. The air entering inlet 2? may be outdoor air or air whose temperature and/or moisture content has been reduced such as that obtainable from outlet iii of another unit or it may be waste air discharged from the conditioned space or mixtures of the above air qualities.

Fig. 5 illustrates in further detail how the evaporative cooling jacket 3 surrounds and insulates the dehumidification section 2.

- Fig. 4, for example, showstwo conditioning units A and B each having a dehumidification chamber 2 receiving air from a duct 4 and discharging conditioned air from the outlet l3 and each surrounded by an evaporative cooling jacket 3 and being constructed and operated in accordance with Figs. 1, 2 and 3. Y

The unit A may receive outdoor air into the duct l for dehumidification and cooling in the so as to provide cooler water for use in the dehumidification section 2 of the unit B than if only atmospheric air were used to cool the water in unit B.

In this manner a lower temperature level is provided in the unit B than in the unit A and air of lower moisture content and temperature is discharged from the outlet I 3 of the unit 3 than can be provided in the unit A. r

By using two or more units connected as illustrated in Fig. 4, air of any desired degree of temperature and moisture content within the limits of human comfort may be provided for discharge from the last unit of the series, into the conditioned space which is illustrated at C in Fig. 4.

Also in this arrangement, it is possible to recirculate the air from the conditioned space through one of the conditioning units, and thereby avoid the expense of having to condition all outside air. As illustrated, air from the conditioned space C may be drawn out through the duct 50 and conveyed into the inlet 'duct d of one of the conditioning units such as B and by means of suitabledampers 5i and 52 the amount of inside air recirculated may be proportioned to the amount of outside air taken in through the outside air duct 53 to provide any desired proportion of fresh to recirculated air.

The blowers 28a and 28b might be in the inlet duets 2?! but I'prefer the placement of them inv the positions as shown. For example, in the case of blower. 28a the heat generated by forcing the air through the evaporative jacket of unit A is discharged to the atmosphere and is not a burden upon this cooling jacket. The blower 28b draws air into the dehumidifying chamber 2 of unit A and thence through jacket 3' of unit B and the heated air is discharged to the atmosphere to circulating through the dehumidifying sections 2 in a condition of proper concentration, a specified portion thereof, for example, one-fifth 0A). to one-sixth /6) is diverted through the pipes $5 to the reconcentrator 55, which may serve one or more conditioning units of the type illustrated by A and B, where heat is applied to the hygroscopic solution to drive ofi the water absorbed from the air and the reconcentrated hygroscopic solution returned through the pipes 56 to the sump l2 for circulation through the dehumidification section'Z. The operation and control for the reconcentrator is described in greater detail in the copending applications Ser. No. 98,646 and 144,630.

In the embodiment of the invention illustrated I I in Fig. 6, the dehumidification section is indicated at 2 andthe evaporative cooling jacket at 3.

The heat exchanger I and its pumping circuit receives soft water or other suitable liquid from an expansion tank 60 through the pipe 6|. This liquid is circulated through-the pipes 62, pump 63 and coil 64 immersedin the evaporative water on the bottom 20 of the jacket 3 and pipe to the pipes 8 in the heat exchanger '7 and back through the pipe 62. In this way the liquid which is not evaporatively cooled may be continuously circulated through the heat exchanger I.

and is cooled in its flow through the coil 64 immersed in the cooled water in the bottom of the evaporative cooling jacket 3, to thereby prevent the formation of scale in the conduits in the heat exchanger I. The coils 64 as shown extend three- 7 fourths of the way around the chamber 2 to provide ample heat transfer surfaces. Ordinary or even hard water may be circulated through the cooling jacket 3 by the pump 32 as described in connection with Fig. 1 and the hygroscopic solution maybe circulated over the surfaces of the heat exchanger 1 by the pump 3|. But for the separate liquid circuit, the operation of the apparatus illustrated in Fig. 6 is essentially similar to that illustrated in Figs. 1 to 3.

The pump 3| withdraws the hygroscopic liquid from the sump I2 through the pipe 43 and discharges it through pipes 44 and 45 to the pipes 5 and spray nozzles 6 from which it flows concurrently with the air through the heat exchanger 1 to dehumidiiy the air. The pump 32 withdraws cooled water from the bottom 20 of the jacket 3 through the pipe 33 and pumps it, through the pipe 34a, to the header 2| where it flows around the top of the jacket 3 and is sprayed by the nozzles 23 into the air stream passing upward through the jacket 3, where heat is removed from the apparatus by evaporation of part of the water and the remainder is returned to the pool in the bottom 20 of the jacket 3. Here it withdraws heat from the liquid flowing through the immersed coils 64 on its way to the heat exchanger I.

This type of evaporative jacket containing cooling coils for heat exchange between the evaporative water and .the' cooling liquid passed through the conduits 8 of heat exchange unit I is also of advantage when for example. the evaporative jacket 3 of a unit is to be operated under a vacuum. In such a case the duct 21 is closed or not provided and a means of evacuating the jacket is connec ed to duct 28.

In the embodiment of my invention illustrated in Fig. 7, the evaporative cooling jacket 30 is shown app ied to the liquid phase dehumid fier 2c of a combined liquid and solid phase de umid fier 'I'I of th type illustrated and described in copending application Ser. No. 57,148. It will be unde stood. however, that the evaporative cooln jacket 30 m y be made to surround the entire de umid fier Ill if desired.

In this embodiment the air to be de umidified enters the duct 40 and contacts with the sprays 8c of hygroscopic liquid and flows concurrently with the hygroscopic liquid through the passages of the heat exchange unit Ia and past the spray eliminator Ilc into the solid phase dehumidification section of the dehumidifier I0.

In the solid phase section of the dehumidifier the air passes through the beds II. 72 and I3 of solid dehumidification material, such as calcium chloride, and is discharged through the ducts I4 and I5 to the space to be conditioned. Between the beds 'II and I2 and the beds I2 and I3 the air passes through heat exchange units I6 and II where part of the heat of dehumidification generated in the beds of solid material is removed.

As the solid dehumidification material, in the beds 'Il, I2 and I3 is liquefied by the, moisture removed from the air passing therethrough, the liquefied material and small residual particles of solid material drop through the screens I8 into the pool or sump l2c of liquid hygroscopic material in the unit I0 from which it is picked up by the suction line I9 of the pump and conveyed through the pipe 8| to the spray nozzles 60. If too much liquid hygroscopic material accumulates in the sump I20 the float 82 energizes an electrical circuit 83a and 83b to the electrically controlled valve 84 in the pipe am to open this valve and permit excess hygroscopic liquid to be discharged through the pipe Bib. As the solid material is dissolved in the beds II, I2 and 13, additional solid material feeds down from the bins Ila, Ho and 13a.

The motor drives a fan in the conduit I5 and also by means of a belt connection 85a drives the pump 80, all as more completely described in said copending application Ser. No. 57,148. The fan may be so connected to the apparatus to blow air into the duct 40 rather than draw it through the apparatus as shown.

The heat exchange unit 10 and also the heat exchangers I1 and I6 are cooled by water from the evaporative cooling jacket 30 by means of a pump 86 which receives water through the pipe 81 from the bottom 200 of the evaporative cooling jacket 30 and pumps it through the pipe 88 to the heat exchanger II from which it flows through the pipe 89 into the heat exchanger 16 and thence through the pipe into the bottom of the heat exchanger Ic. From the top of the heat exchanger 1c the water flows through the pipe iii to the manifold 2Ic and spray nozzles 230 where it is sprayed down over the packing material 240 in the jacket 30. At the same time air from any suitable source is being drawn through the inlet 21d of the evaporating cooling jacket 30- and discharged through the outlet 28c preferably to the outdoor atmosphere by the fan 2811 to cool the water which is discharged from the nozzles 23c in the manner described in connection with Figs. 1 to 5. A float valve 4| controlled by a float 42 admits water from the pipe 40 to the bottom and another portion through the dehumidifier section 2 of the unit B to be further cooled and dehumidified. Suitable dampers 21c and 56a are provided for proportioning the air flow through the evaporative cooling jacket and the dehumidifier section of the unit B and the latter may be smaller than the unit A as it does not have as much air to cool and dehumidity and the airhas already been partially treated. Fans 28a in the outlets 28 for the evaporative cooling jackets provide air flow through these jackets and a fan 51 in the duct 56 provides flow through this duct.

While I have described preferred forms 01' embodiment of my invention, it will be understood that these particular forms oi. embodiment are for illustration only and that various modifications and changes may be made in these embodiments, all within the spirit'oi' my invention or the scope of the claims.

I claim:

1. The process of cooling a "gaseous fluid and dehumidifying it to an unsaturated state, which includes flowing the fluid through a dehumidifying zone containing a dehumidifying agent, cooling said fluid to progressively lower temperatures during said flow by transferring heat of moisture absorption to a cooling liquid within said zone but out of contact with said fluid, cooling said liquid in an evaporating zone in heat conducting =relationship to said absorbing zone, by removing heat from said evaporating zone to progressively lower temperatures in step with those in the absorbing zone, and separating the gaseous fluid from the dehumidifying agent at the lowest temperature reached. v

2. The process of cooling and dehumidifying a gaseous fluid to a moisture unsaturated state, which includes flowing a cooling liquid upwardly through a conduit in a moisture absorbing zone countercurrent to the flow of the gaseous fluid and to progressively higher temperatures, and

thence downwardly through an evaporating zone separated from said absorbing zone by a heat conducting wall and to progressively lower temperatures, and delivering the gaseous fluidfrom the absorbing zone where said zone is cooled to its lowest temperature by the cooling liquid in both said conduit and said evaporating zone.

3. The method of dehumidifying air or other gases to a moisture unsaturated state, which comprises flowing air in directed paths through two zones separated by a heat conducting wall, passing,

a hygroscopic solution through one of said zones and concurrent with the air flowing therethrough to absorb moisture from said air and generate heat, circulating water out of contact with but in heat transfer relationship to the hygroscopic solution and countercurrent to the flow thereof to progressively cool the solution and warm the water, delivering said warm water into the upper part of the other zone to flow countercurrent to and in contact with the air in said last mentioned zone topartially evaporate the water and absorb heat by said air, thereby cooling the remaining water and said heat conducting wall, and circulating said remaining water for removing further heat from said solution.

d. The process of dehumidifying a gaseous fluid to a moisture unsaturated state by means of a hygroscopic material, which comprises passing the gaseous fluid .in contact with said material in a dehumidifying zone, circulating water through cooling elements within said zone and in heat transfer relationship to said gaseous fluid and said hygroscopic material, evaporating a portion of the water delivered from said elements closely adjacent to the outer surface of a heat conducting boundary wall of said zone to abstract heat from said zone, cool the water and prevent absorption of heat from outside sources to said zone, and returning the unevaporated portion of the water to said cooling elements.

5. The process of dehumidifying a gaseous fluid to a moisture unsaturated state by means of a hygroscopic solution, which includes distributing hygroscopic solution throughout a current of said gaseous fluid to form an intimate mixture, preserving intimate contact of the solution and gaseous fluid of said mixture in divided form by flowing them as thin streams in the same general direction, progressively cooling and removing the heat of moisture absorption from said flowing mixture by circulating a cooling liquid between said streams,- and out of contact with but in direct heat conducting relationship to and countercurrent to the said streams, evaporating liquid in contact with the outside of a heat conducting boundarywall in heat conducting relationship to said flowing mixture of gaseous fluid and solution to progressively cool and additionally abstract heat therefrom and prevent absorption of heat to said mixture from outside sources,

and returning the unevapoi'ated portion of said liquid adjacent to said boundary wall for iurther evaporation.

6. The process of dehumidifying a gaseous fluid .to a moisture unsaturated state by means of a hygroscopic liquid, which includes distributing hygroscopic liquid throughout a current of said gaseous fluid to form an intimate mixture, preserving intimate contact of the hygroscopic liquid and gaseous fluid of said mixture in divided form by flowing them as thin streams in the same general direction, progressively cooling and removing the heat of moisture absorption from said flowing mixture by circulating water between said streams, and out of contact with but in direct heat conducting relationship to and countercurrent to the said streams, evaporating some of the water adjacent to but outside of a heat conducting boundary wall in heat conducting relationship to said flowing mixture of gaseous fluid and hygroscopic liquid to progressively cool and additionally abstract heat therefrom and prevent 7 absorption of heat to said mixture from outside sources and cool the water, and delivering the unevaporated portion of the water for recirculation between said streams.

7. The method of removing a vaporous constituent from a gas by a suitable liquid absorbent, which comprises dividing the gas into a plurality of streams in an absorbing zone, flowing absorbent liquid in concurrent contact as thin films with said gas streams, flowing water in direct contact with a directed countercurrent stream of moisture absorbing. gas through a humidifying zone in direct heat conducting relationship with said absorbing zone to cool the water, removing heat through said films of absorbent liquid to a countercurrent of said cooled water out of contact with but in heat exchange relationship to said films, and separating the said vaporous constituent from the absorbing liquid.

8. The process for dehumidifying gaseous fluid such as air by the use of hygroscopic material, which includes passing the gaseous fluid in com tact with the hygroscopic material in a dehumidi- Tying and cooling zone, passing a portion otthe dehumidifled gaseous fluid in contact with hygroscopic material in a second dehumidifying zone, passing the remainder of said gaseous fluid through a humldliying zone separated from said second dehumidifying zone by a heat transfer wall, evaporating water in said humldifying zone to cool the water, cool said second dehumidifying zone and prevent absorption of heat to said heat transfer wall from outside sources, and circulating a cooling fluid through said second dehumidifying zone out of contact with but in heat second dehumidifying zone.

' transfer relationship to the gaseous fluid in said I s 9. The method of independently controlling humidifying zone, removing heat from said coolingliquid in a cooling zone as water vapor, said cooling zone being in heat exchange relation with said dehumidifying zone, separating the dried and cooled gas from hygroscopic liquid, discharging said gas to said enclosed space, discharging a part at least of said hygroscopic liquid to a concentrating zone, returning concentrated hygroscopic liquid to said dehumidifying zone to form further films and regulating the temperature of the enclosed space by varying the temperature level of the water vapor in the cooling zone and regulating the humidity of the enclosed space by varying the concentration of the hygroscopic liquid used to form said films.

10. In an air conditioning apparatus of the type described, a dehumidifying section having a passage through which the air to be conditioned may be passed in contact with dehumidifying materials, cooling conduits through which water may be passed in heat conducting relation to but out of contact with said dehumidifying materials to remove heat thereirom, an evaporative water cooling section separated from said dehumidifying section by a heat conducting wall, means for delivering water for evaporation in, said cooling section, and means to deliver cooled water to said cooling conduits.

. 11. In an air conditioning apparatus of the type described, a dehumidifying section having a passage through which the air to be conditioned may be passed in contact with dehumidifying materials, cooling conduits through which water may be passed in heat conducting relation to said dehumidifying materials to remove heat therefrom, a water cooling section surrounding said dehumidifying section and in direct heat conducting relation therewith, means to spray said water,

after passage through the cooling conduits in said dehumidifying section, into said water cooling section, means to pass other air in counterdirection through said waterin the water cooling section to cool said water, means to return the cooled water. to said cooling conduits, and means to introduce water to make up for that lost by evaporation.

12. In an air conditioning apparatus of the type described, a dehumidifying section, having passages through which the air to be conditioned may be passed in a plurality of fine streams in contact with flowing films of hygroscopic solution, cooling conduits through which water may be passed in indirect heat exchange relation to said films of hygroscopic solution to remove heat therefrom anda water cooling section adjacent said dehumidifying "section and separated therefrom by a heat conducting partition, means to spray said water after passage through the cooling conduits in said dehumidiiying section into said water cooling section, means to pass other airin countercurrent direction through said water in the water cooling section to cool said water, and means to return the recooled water to said cooling conduits.

13. In an air conditioning apparatus of the type described, a dehumidification section, means to pass air therethrough, means to contact the dehumidification section, means to pass said water after circulation through the dehumidification section through said evaporative jacket, and means to return water cooled in said evaporative 'jacket to the conduit in said dehumidification section.

14. In an air conditioning apparatus of the type -described, a dehumidification section, means to pass air to be conditioned therethrough, means to contact the air in fine streams with flowing films of hygroscopic solution therein, a cooling water conduit in the dehumidification section to remove heat from the air and hygroscopic solution, means to separate said air and hygroscopic solution, means to recirculate the hygroscopic solution through the dehumidification section in ,contact with further air to be conditioned, an evaporative cooling jacket for said dehumidification section, and means to pass said water after circulation through the dehumidification section through said evaporative cooling jacket to cool said water for recirculation through the dehumidification section.

15. In an air conditioning apparatus of the type described, a dehumidification section, means to pass air therethrough, means to contact the air with dehumidii'ying materials therein, a cooling water conduit in the dehumidification section to remove heat from the air and dehumidifying materials, an evaporative cooler surrounding a portion of said dehumidificationsection,

and means to pass said water after circulation through the dehumidiflcation' section through said evaporative cooler, means in said evaporative cooler to divide the water into fine portions,

means to pass air in contact withsaid water to contact with said material and through which water-may be circulated to remove heat from said cool the water by evaporation, and means to hygroscopic materials, means to cool said water i I and further remove heat from said hygroscopic materials comprising an evaporative cooling chamber separated by a heat conducting wall from said section, means to maintain a supply of water in said cooling chamber, means associated with said evaporative cooling chamber to reduce the partial pressure of water therein, and means to circulate water through said evaporative cooling chamber and heat exchange units.

' CHARLES R. DOWNS. 

